Automatic lane following systems have been demonstrated operating at motor way speeds. Such systems certainly prevent lane departure while lane markings (usually the white painted lines) are present. A controller of the systems estimates the vehicle's lateral position in relation to the lane markings. An optical sub-system or a video camera or equivalent sensor is mounted on a vehicle and used to detect the lane markings. An actuator coupled to the steering mechanism is used to control the steering position of the front road wheels. The lane following system is enabled when a system main switch is closed. When a direction indicator of the vehicle is actuated, the lane following system is disabled.